1. Field of the Invention
The present invention relates to an image stabilizer, and more particularly, to a micro-optical image stabilizer.
2. Description of the Prior Art
Nowadays many digital cameras emphasize on the stabilization function. One of the stabilization methods involves equipping the image sensor (such as CCD and CMOS) with an image stabilizer so as to stabilize the captured image when the image sensor is not stable. However, as the digital camera is getting smaller, the size of the image stabilizer is also getting smaller. Hence, it is proposed with the image stabilizer utilizing Micro-Electro-Mechanical System (MEMS) techniques in the prior art.
Please refer to FIG. 1. FIG. 1 is a diagram illustrating an image stabilizer 100 of MEMS. The image stabilizer 100 comprises an image processing circuit 110, an actuator control circuit 120, 4 sets of electrostatic actuators 131-134, a substrate 170, a carrier 150, an image sensor 160, and a flexible printed circuit 140. The image sensor 160 comprises an image sensing area 161. The actuator control circuit 120 is coupled to the electrostatic actuators 131-134 for controlling the movements of the electrostatic actuators 131-134. One end of each of the electrostatic actuators 131-134 is fixed above the substrate 170 and the other end of each of the electrostatic actuators 131-134 is fixed to the carrier 150. The distance between the two ends of each of the electrostatic actuators 131-134 is controlled by the actuator control circuit 120. Consequently, the position of the carrier relative to the substrate is controlled by the actuator control circuit 120. Take the electrostatic actuator 133 for example, the electrostatic actuator 133 comprises a fixed component 133a and a moveable component 133b. The fixed component 133a is fixed above the substrate 170 and the moveable component 133b is fixed to one side of the carrier 150 (as shown in FIG. 1). The distance between the fixed component 133a and the moveable component 133b is controlled by the actuator control circuit 120. For example, the higher the control voltage of the actuator control circuit 120 transmitted to the electrostatic actuator 133, the closer between the fixed component 133a and the moveable component 133b, and vice versa. Thus, the distance D is controlled by the actuator control circuit 120. The other 3 sets of the electrostatic actuators 131, 132, and 134 are also controlled in the same manner. In this way, the actuator control circuit 120 respectively controls the electrostatic actuators 131-134 for moving the carrier 150 relative to the substrate 170. The image sensor 160 is fixed above the carrier 150 but not electrically coupled to the carrier 150. Therefore, the image sensor 160 moves as the carrier 150. The image sensing area 161 is disposed for sensing optical signals of an image, which means the image sensing area 161 senses the image, and accordingly generating electrical signals. The image processing circuit 110 is coupled to the image sensor 160 through the flexible printed circuit 140 for receiving the electrical signals from the image sensor 160 and accordingly generating digital signals of the image. Thus, when the substrate 170 is moving, the actuator control circuit 120 transmits control signals to the electrostatic actuators 131-134 so as to move the carrier 150 in the opposite direction. Thus, the movement of the substrate 170 does not affect the image sensor 160 and the captured images are stabilized.
Please refer to FIG. 2. FIG. 2 is a diagram illustrating the fabrication of the conventional image stabilizer 100. As shown in FIG. 2, after the electrostatic actuators 131-134 and the carrier 150 are fabricated onto the substrate 170, the image sensor 160 is attached onto the carrier 150, and then the flexible printed circuit 140 is electrically and mechanically coupled to the image sensor 160. The image sensor 160 is equipped with a plurality of conducting pads 162 and the flexible printed circuit 140 is correspondingly equipped with a plurality of pins 141. In fabrication, the conducting pads 162 is applied with tin paste, then the flexible printed circuit 140 is fixed above the conducting pad 162 with glue, and the combination of the flexible printed circuit 140 and the image sensor 160 are heated so as to couple the pin 141 of the flexible printed circuit 140 onto the conducting pad 162 of the image sensor 160.
It is known from the above that the conventional image stabilizer 100 needs two steps for fabrication of the image sensor: 1. glue the image sensor 160 onto the carrier 150, and 2. couple the flexible printed circuit 140 onto the image sensor 160. The two steps are complicated for production, which is inconvenient.
Furthermore, in the conventional image stabilizer 100, because the flexible printed circuit 140 is electrically and mechanically coupled to the image sensor 160, when the movement of the carrier 150 relative to the substrate 170 is generated, the presence of the flexible printed circuit 140 interferes with the movement. For example, the flexible printed circuit 140 generates force onto the carrier 150 when the flexible printed circuit 140 is squeezed or pulled, which interferes the movement of the carrier 150. Besides, it is unknown of the force generated by the flexible printed circuit 140. Therefore, the position of the carrier 150 is also affected by the flexible printed circuit 140, which is different from the ideal position.